1. Field of the Invention
The present invention relates to a socket for an electric part, which is designed so that an electric part such as a semiconductor device or the like is detachably retained thereon, and particularly, to a socket for an electric part, which is designed so that terminals of the electric part are electrically connected to contact portions of contact pins of the socket for the purpose of carrying out a performance test for the electric part.
2. Description of the Related Art
In order to carry out the performance test for an electric part such as a semiconductor device, many electric part sockets are conventionally used to electrically connect terminals of the electric part to a printed wiring board of a measurer.
Such a socket for an electric part includes a top plate disposed on a socket body for placement of the electric part, contact pins disposed on the socket body and each having a pair of resilient pieces, a slide plate disposed between the top plate and the socket body for sliding movement in a horizontal direction, and an upper operating member movable vertically relative to the socket body in order to move the slide plate.
In placing the socket into use, the upper operating member is lowered to slide the slide plate horizontally, thereby resiliently deforming one of the resilient pieces constituting the contact pin to open out an upper end thereof. Thereafter, the upper operating member is raised with the electric part placed on the top plate, thereby returning the slide plate to its original position and releasing a pressing force to the contact pin. Thus, the retracted resilient piece of the contact pin is returned to its initial position, whereby the upper end of each of the contact pins clamps corresponding one of the terminals of the electric part. In this manner, the contact portions formed at the upper end are brought into abutment against the terminal to provide an electric connection.
In such conventional socket, however, only one of the resilient pieces of the contact pin is resiliently deformed and for this reason, there is a possibility of a scattering of the opening-out and closing of the contact pin.
Specifically, if only one of the resilient pieces constituting the contact pin is pressed by moving the slide plate, a reaction force is applied from such resilient piece to the slide plate to lose the balance of engagement of the upper operating member for sliding the slide plate in the horizontal direction with the socket body, thereby causing the scattering the opening-out and closing of the contact pin.
In a state in which the opening-out and closing of the contact pin is not uniform, as described above, it is difficult to clamp the terminals of the electric part by the contact pins, respectively, resulting in a reduced operating efficiency.
Another problem is as follows: When only the one resilient piece of the contact pin is resiliently deformed for opening-out of its upper end, a increased deviation is produced between a position at the time of insertion of each of the terminals of the electric part into the opened-out upper end of the contact pin and a position at the time of clamping of the terminal between the contact portions at the upper end. Therefore, in order to the contact the electric part and guide portions formed on the top plate on the socket body for locating the electric part in a predetermined position, it is necessary to provide a large gap between the electric part and the guide portions, resulting in a poor mountability of the electric part to the electric part socket.
Accordingly, it is an object of the present invention to provide a socket for an electric part, wherein the resilient pieces constituting each of the contact pins can be opened out in equal resiliently deformed amounts by equally pressing the resilient pieces.
To achieve the above object, according to the present invention, there is provided a socket for en electric part, comprising a socket body, a plurality of contact pins disposed on the socket body and each capable of clamping corresponding one of terminals of an electric part placed on a rest face of the socket body between contact portions formed at tip ends of a pair of resilient pieces, and two slide plates mounted for sliding movement in different directions relative to the socket body by an urging motion of the upper operating member, so that the slide plates are slid in the different directions by applying a pressing force for urging the upper operating member downwards to resiliently deform the resilient pieces in spacing directions, thereby opening-out the contact portions of the contact pin, and so that the slide plates are slid back to their original position by releasing the pressing force to the upper operating member, thereby decreasing the resilient deformation of the resilient pieces in approaching directions to move the contact portions of the contact pin toward each other, thus clamping each of the terminals of the electric part.
With the above arrangement, the upper end of the contact pin can be opened out in center symmetry by displacing the resilient pieces in the same amount in the different directions. Thus, the positions at the time of insertion of each of the terminals of the electric part into the upper end and at the time of clamping of the terminal on the upper end cannot be changed from each other, thereby enabling the enhancement of the mountability of electric part.
According to another aspect of the present invention, in addition to the above feature, pressing members are formed between the two slide plates and interposed between the pair of resilient pieces for applying resiliently deforming forces to the corresponding resilient pieces at substantially symmetric locations during opening-out of the contact portions of each of the contact pins.
With the above arrangement, it is possible to ensure that the reaction force from the pressing force on the slide plate is equal at both of the resilient pieces. Therefore, it is possible to maintain the balance of engagement of the socket body with the upper operating member for sliding the slide plates in the horizontal direction, thereby preventing a scattering from being produced in opening-out and closing of the contact pin.
The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.